transport in humans

• lymphocytes

  a type of white blood cell that produces antibodies and antitoxins
• lymphocyte detects antigens and produces complimentary antibodies

  antibodies clump the pathogens

  which makes it easier for phagocytes to engulf

  also produce antitoxins which neutralize toxins produced by harmful bacteria
• an antigen is the protein on the surface of a pathogen that the lymphocyte detects
• antibody

  protein released by lymphocytes that bind to antigens and cause the pathogens to clump or marks them for destruction
• memory cells

  specific lymphocytes that remain in the immune system after the pathogen is removed as they have the correct antibodies for that pathogen
• phagocytes

  type of white blood cell that destroys pathogens
• phagocytes enclose a pathogen in the phagosyme and engulf it (phagocytosis) and then releases digestive enzymes to destroy the pathogen
• the function of blood is to transport substances around the body
• blood is a tissue because it is a collection of similar specialised cells that serve a particular function
• red blood cells

  carry oxygen around the body
• white blood cells have a nucleus and red blood cells dont
• platelets

  help blood to clot at a wound which prevents excess blood loss and microorganisms from entering the wound
• platelets clot blood by releasing chemicals that cause soluble fibrin proteins to convert into insoluble. the fibrin forms an insoluble mesh across wound
• blood is made up of red blood cells, white blood cells, plasma, platelets
• plasma

  straw coloured liquid which carries everything in blood (red blood cells, white blood cells, platelets, digested food (glucose and amino acids), carbon dioxide, urea, hormones, heat energy)
• digested food is transported from where they are absorbed in the small intestine to cells of the body by the plasma
• carbon dioxide is transported from respiring tissues to the lungs by the plasma
• urea is transported from the liver to the kidneys by the plasma
• hormones are transported from the endocrine glands to target organs/tissues by the plasma
• heat energy is transported from respiring tissues to cooler body regions (skin) by plasma
• red blood cells have a bioncave shape to increase surface area to volume ratio so they can absorb more oxygen
• red blood cells don't have a nucleus so they can have more room for haemoglobin to carry oxygen
• red blood cells have a red pigment called haemoglobin which bonds to oxygen and carries it and then can release the oxygen to cells
• vaccines work by giving someone a weakened pathogen so they lymphocytes can produce memory cells for that virus and if they catch the virus, antibodies will be produced sooner, faster and a greater quantity
• multicellular organisms need a circulatory system as they are too big and have a too small surface area to volume ratio so they cant rely on diffusion
• the atrium is at the top of the heart, the ventricles are at the bottom. there are valves between them to stop blood flowing backwards
• pulmonary artery -> lungs -> pulmonary vein -> left atrium -> left ventricle -> aorta -> body -> vena cava -> right atrium -> right ventricle -> pulmonary artery
• blood goes into the atrium first, then it contracts and blood goes through the valve into the ventricle, then the ventricle contracts and blood goes out the top of the heart through the aorta or pulmonary artery